fs/jffs2/read.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright © 2001-2007 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/crc32.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/mtd/mtd.h>
  17 #include <linux/compiler.h>
  18 #include "nodelist.h"
  19 #include "compr.h"
  20
  21 int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
  22                      struct jffs2_full_dnode *fd, unsigned char *buf,
  23                      int ofs, int len)
  24 {
  25         struct jffs2_raw_inode *ri;
  26         size_t readlen;
  27         uint32_t crc;
  28         unsigned char *decomprbuf = NULL;
  29         unsigned char *readbuf = NULL;
  30         int ret = 0;
  31
  32         ri = jffs2_alloc_raw_inode();
  33         if (!ri)
  34                 return -ENOMEM;
  35
  36         ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
  37         if (ret) {
  38                 jffs2_free_raw_inode(ri);
  39                 printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);
  40                 return ret;
  41         }
  42         if (readlen != sizeof(*ri)) {
  43                 jffs2_free_raw_inode(ri);
  44                 printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
  45                        ref_offset(fd->raw), sizeof(*ri), readlen);
  46                 return -EIO;
  47         }
  48         crc = crc32(0, ri, sizeof(*ri)-8);
  49
  50         D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
  51                   ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
  52                   crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
  53                   je32_to_cpu(ri->offset), buf));
  54         if (crc != je32_to_cpu(ri->node_crc)) {
  55                 printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
  56                        je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
  57                 ret = -EIO;
  58                 goto out_ri;
  59         }
  60         /* There was a bug where we wrote hole nodes out with csize/dsize
  61            swapped. Deal with it */
  62         if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
  63             je32_to_cpu(ri->csize)) {
  64                 ri->dsize = ri->csize;
  65                 ri->csize = cpu_to_je32(0);
  66         }
  67
  68         D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
  69                 printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
  70                        len, ofs, je32_to_cpu(ri->dsize));
  71                 ret = -EINVAL;
  72                 goto out_ri;
  73         });
  74
  75
  76         if (ri->compr == JFFS2_COMPR_ZERO) {
  77                 memset(buf, 0, len);
  78                 goto out_ri;
  79         }
  80
  81         /* Cases:
  82            Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
  83            Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
  84            Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
  85            Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
  86         */
  87         if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
  88                 readbuf = buf;
  89         } else {
  90                 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
  91                 if (!readbuf) {
  92                         ret = -ENOMEM;
  93                         goto out_ri;
  94                 }
  95         }
  96         if (ri->compr != JFFS2_COMPR_NONE) {
  97                 if (len < je32_to_cpu(ri->dsize)) {
  98                         decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
  99                         if (!decomprbuf) {
 100                                 ret = -ENOMEM;
 101                                 goto out_readbuf;
 102                         }
 103                 } else {
 104                         decomprbuf = buf;
 105                 }
 106         } else {
 107                 decomprbuf = readbuf;
 108         }
 109
 110         D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
 111                   readbuf));
 112         ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
 113                                je32_to_cpu(ri->csize), &readlen, readbuf);
 114
 115         if (!ret && readlen != je32_to_cpu(ri->csize))
 116                 ret = -EIO;
 117         if (ret)
 118                 goto out_decomprbuf;
 119
 120         crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
 121         if (crc != je32_to_cpu(ri->data_crc)) {
 122                 printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
 123                        je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
 124                 ret = -EIO;
 125                 goto out_decomprbuf;
 126         }
 127         D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
 128         if (ri->compr != JFFS2_COMPR_NONE) {
 129                 D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
 130                           je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
 131                 ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
 132                 if (ret) {
 133                         printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
 134                         goto out_decomprbuf;
 135                 }
 136         }
 137
 138         if (len < je32_to_cpu(ri->dsize)) {
 139                 memcpy(buf, decomprbuf+ofs, len);
 140         }
 141  out_decomprbuf:
 142         if(decomprbuf != buf && decomprbuf != readbuf)
 143                 kfree(decomprbuf);
 144  out_readbuf:
 145         if(readbuf != buf)
 146                 kfree(readbuf);
 147  out_ri:
 148         jffs2_free_raw_inode(ri);
 149
 150         return ret;
 151 }
 152
 153 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 154                            unsigned char *buf, uint32_t offset, uint32_t len)
 155 {
 156         uint32_t end = offset + len;
 157         struct jffs2_node_frag *frag;
 158         int ret;
 159
 160         D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
 161                   f->inocache->ino, offset, offset+len));
 162
 163         frag = jffs2_lookup_node_frag(&f->fragtree, offset);
 164
 165         /* XXX FIXME: Where a single physical node actually shows up in two
 166            frags, we read it twice. Don't do that. */
 167         /* Now we're pointing at the first frag which overlaps our page
 168          * (or perhaps is before it, if we've been asked to read off the
 169          * end of the file). */
 170         while(offset < end) {
 171                 D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
 172                 if (unlikely(!frag || frag->ofs > offset ||
 173                              frag->ofs + frag->size <= offset)) {
 174                         uint32_t holesize = end - offset;
 175                         if (frag && frag->ofs > offset) {
 176                                 D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
 177                                 holesize = min(holesize, frag->ofs - offset);
 178                         }
 179                         D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
 180                         memset(buf, 0, holesize);
 181                         buf += holesize;
 182                         offset += holesize;
 183                         continue;
 184                 } else if (unlikely(!frag->node)) {
 185                         uint32_t holeend = min(end, frag->ofs + frag->size);
 186                         D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
 187                         memset(buf, 0, holeend - offset);
 188                         buf += holeend - offset;
 189                         offset = holeend;
 190                         frag = frag_next(frag);
 191                         continue;
 192                 } else {
 193                         uint32_t readlen;
 194                         uint32_t fragofs; /* offset within the frag to start reading */
 195
 196                         fragofs = offset - frag->ofs;
 197                         readlen = min(frag->size - fragofs, end - offset);
 198                         D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
 199                                   frag->ofs+fragofs, frag->ofs+fragofs+readlen,
 200                                   ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
 201                         ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
 202                         D2(printk(KERN_DEBUG "node read done\n"));
 203                         if (ret) {
 204                                 D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
 205                                 memset(buf, 0, readlen);
 206                                 return ret;
 207                         }
 208                         buf += readlen;
 209                         offset += readlen;
 210                         frag = frag_next(frag);
 211                         D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
 212                 }
 213         }
 214         return 0;
 215 }
 216